A rotatable connector device which is mountable on a vehicle such as an automobile or the like includes a cable housing having a stator and a rotator which are coaxially attached to each other so as to be rotatable with respect to each other.
In the cable housing of such a rotatable connector device, the stator is fixed to a vehicle body and the rotator is attached to a steering wheel. In addition, the rotatable connector device includes flat cables accommodated in an accommodation space in the cable housing. Owing to this structure, the rotatable connector device electrically connects, for example, a horn module and an airbag module provided on the side of the steering wheel and a power supply on the vehicle body side to each other via the flat cables.
Patent Document 1, for example, describes a rotatable connector device including a retainer, located on a bottom surface of the accommodation space, for guiding the flat cables to rotate around an axis of the steering wheel. Such a retainer includes a plurality of rotatable rollers. The plurality of rotatable rollers assist the flat cables in being rotated in the accommodation space in a winding or rewinding direction, so that the rotatable connector device can follow the steering operation to rotate smoothly.
A rotation shaft of each of the rotatable rollers described in Patent Document 1 has a snap-fit structure, and is coupled to a bearing of the retainer in a snap-fit manner (see FIG. 3 of Patent Document 1).
In a radial-direction cross-section of a sliding part along which the rotation shaft of such a rotatable roller and the bearing of the retainer slide against each other (see FIG. 8A), a leg 455 having the snap-fit structure has a cross-sectional shape which is along an inner circumferential surface 43b of the bearing (see FIG. 8B).
While the rotatable connector device including the rotatable rollers is rotated, if a foreign object is stuck in the sliding part of the retainer and each rotatable roller, the foreign object is not easily removed because the size of the area along which the rotation shaft and the bearing slide against each other is large. This causes a problem that the rotatable rollers cannot rotate smoothly. In addition, due to the foreign object stuck in the sliding part, burr or the like is generated in the sliding part on the bearing side or the rotation shaft side, which influences the rotation of the rotatable rollers.
Such a foreign object may enter from outside during the assembly of the rotatable connector device, or may be caused by burr or the like which is generated during the molding of the retainer or the rotatable rollers and is not removed thereafter.